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XP95

FIRE DETECTORS LIMITED

INTRINSICALLY SAFEANALOGUE ADDRESSABLESMOKE & HEAT DETECTORSBASEEFA approved E EX ia IIC T5 (T4 at Ta <– 60°C)ENGINEERING PRODUCT GUIDE

Apollo Fire Detectors manufactures fire detectors designedfor use in hazardous areas. This Product Guide givesinformation on the intrinsically safe (I.S.) version of the XP95analogue, addressable range of smoke and heat detectorswhich have been approved by BASEEFA. The approvals are toBS EN 60079-0:2004, BS EN 50284:1999, BS EN 50020:2002and BS EN 60079-26:2004. All types are certified to EEx ia IICT5 at ambient temperatures up to 40°C, or T4 at ambienttemperatures up to 60°C.

The range comprises ionisation and optical smoke detectors,a temperature detector, a detector base and a compatiblemanual call point. There is also a choice of two translatorswhich ensure integrity of communication between detectorsand control equipment within the constraints of anintrinsically safe system.

The guide also provides information on intrinsic safety, theapplication and installation of the products and thecertification documentation. Reference is made to otherproduct guides published by Apollo and the Guide to thecare, service and maintenance of Apollo products(publication PP2055). All are available on request.

Information in this guide is given in good faith, but ApolloFire Detectors Limited cannot be held responsible for anyomissions or errors. The company reserves the right tochange specifications of products at any time and withoutprior notice.


XP95 INTRINSICALLY SAFE FIRE DETECTORS


TABLE OF CONTENTS

Intrinsically Safe Products Page 6XP95 I.S. Ionisation Smoke Detector Page 6XP95 I.S. Optical Smoke Detector Page 7XP95 I.S. Heat Detector Page 8XP95 I.S. Base Page 8XP95 I.S. Manual Call Points Page 9

XP95 Intrinsically Safe Communications Protocol Page 10XP95 Protocol Translator Page 10Translator Operation Page 10

System Design Page 12

Types of Safety Barrier Page 13Single Channel Page 13Star-connected A.C. Barrier Page 13Galvanically Isolated Barrier Page 13

Approved Safety Barriers Page 14

Safety Earth Page 15

Wiring and Cable Types Page 15

Maximum Loading of I.S. Circuit Page 16

Installation Page 16

Remote LED Connection Page 16

MiniDisc Remote Indicator Page 17

Servicing Page 18

Approvals Page 18

XP95 I.S. System Drawing Page 19

Introduction to Intrinsic Safety Page 4

Classification of Hazardous Areas Page 4

Zone DefinitionIntrinsically SafeEquipment ApprovalRequired


INTRODUCTION TO INTRINSIC SAFETY

There are many places where an explosive mixture of airand gas or vapour is or may be present continuously,intermittently or as a result of an accident. These are definedas hazardous areas by BS EN 60079, the code of practice forinstallation and maintenance of electrical apparatus inpotentially explosive atmospheres.

Hazardous areas are common in petroleum and chemicalengineering plants and in factories processing and storinggases, solvents, paints and other volatile substances.

Electrical equipment for use in these areas needs to bedesigned so that it cannot ignite an explosive mixture, notonly in normal operation but also in fault conditions. Thereare a number of methods available to achieve this - oilimmersion, pressurised apparatus and powder filling, forexample, but the two in most common use are flameproofenclosures and intrinsic safety.

Flameproof equipment is contained in a box so strong thatan internal explosion will neither damage the box nor be

transmitted outside the box. The surface must remain coolenough not to ignite the explosive mixture.

When flameproof equipment is interconnected, flameproofwiring must be used. This method is most valuable whenhigh power levels are unavoidable but it is not acceptablefor areas in which an explosive gas/air mixture may becontinuously present or present for long periods.

For this reason Apollo fire detectors are made intrinsicallysafe rather than flameproof. Intrinsically safe equipmentoperates at such low power and with such small amounts ofstored energy that it is incapable of causing ignition:

– in normal conditions– with a single fault (for ib classification)– with any combination of two faults (for ia classification)

In any of these conditions every component must remaincool enough not to ignite the gases for which it is approved.

CLASSIFICATION OF HAZARDOUS AREAS

BS EN 60079-10:2003 defines a hazardous area as one inwhich explosive gas/air mixtures are, or may be expected tobe, present in quantities such as to require specialprecautions for the construction and use of electrical apparatus.

The degree of risk in any area is a function of:

• the probability of an explosive mixture being present• the type of gas which may be present• the temperature at which a gas might ignite spontaneously

These are defined in Table 1, Zone Classification, Table 2,Subdivision of Group II Gases and Table 3, TemperatureClassification, respectively.

Zone 0 in which an explosive gas/airmixture is continuously presentor present for long periods Ex ia

Zone 1 in which an explosive gas/air mixture is likely to occur innormal operation Ex ia or Ex ib

Zone 2 in which an explosive gas/airmixture is not likely to occur innormal operation and if it occursit will exist only for a short time Ex ia or Ex ib

XP95 detectors are approved to Ex ia and are suitable for all zones

Table 1 Zone Classification


Representative Gas Other Gases, Liquids, VapoursIntrinsically SafeEquipment ApprovalRequired

Hydrogen Carbon DisulphideAcetylene IIC

Ethylene Butadiene, Formaldehyde,Diethylether IIB or IIC

Methane Acetaldehyde, Acetone,Benzene, Butane, Ethane,Hexane, Heptane, Kerosene,Naphtha, Petroleum,Styrene, Xylene IIA or IIB or IIC

XP95 detectors are approved to IIC and may be used for all gases listed in PD IEC 60079-20:2000.

Table 2 Subdivision of Group II Gases

MaximumTemperature Surface Gases, Liquids Intrinsically SafeClass Temperature Vapours Approval Required

(°C)

T6 85 T6

T5 100 Carbon Disulphide T5 or T6

T4 135 Acetaldehyde, Diethylether,Isopropylnitrate T4 or T5 or T6

T3 200 Hexane, Heptane T3 or T4 or T5 or T6

T2 300 Butane, Butadiene, T2 or T3 or T4 or T5Ethylene or T6

T1 450 Acetone, Ammonia,Benzene, Carbon Monoxide,Ethane, Hydrogen,Methane, Propane, T1 or T2 or T3 or T4Ethylene or T5 or T6

XP95 detectors are approved to T5 at 40°C and are suitable for all gases listed in PD IEC 60079-20:2000.

Table 3 Temperature Classification

XP95 INTRINSICALLY SAFE PRODUCTS

XP95 I.S. Ionisation Smoke Detector

Intrinsically Safe Ionisation Smoke DetectorPart no: 55000-540

The sensing part of the detector consists of two chambers –an open, outer chamber and a reference chamber within.

Mounted in the reference chamber is a low-activity radioactivefoil of Americium 241 which enables current to flow across theinner and outer chambers when the detector is powered up.

As smoke enters the detector, it causes a reduction of thecurrent flow in the outer chamber and hence an increase inthe voltage measured at the junction between the twochambers. This analogue voltage signal is converted to adigital signal by the electronic circuitry and transmitted tothe control panel on interrogation. The micro-processor inthe control equipment then compares the signal with storeddata and initiates a pre-alarm or fire alarm as smoke densityincreases. When a fire condition exists, the panel instructsthe detector to switch on its indicator LED.

Full details of the principles of operation and electricaldescription are published in the XP95 Engineering ProductGuide. Information on the performance of XP95 in adverseenvironmental conditions is also given in this guide. XP95I.S. detectors have the same operating characteristics as thestandard versions.

Technical Data – XP95 Intrinsically SafeIonisationSpecifications are typical and given at 23° C and 50%relative humidity unless otherwise specified.

Technical Data for the I.S. ionisation detector is identicalto that for the standard version, except for theinformation given below:

Detector Part No:55000-540.

Base Part No:45681-215.

Supply Wiring:Two wire supply, polarity sensitive.

Terminal Functions:L1: positive supply.L2: negative supply and remote LED negative.+R: remote LED positive.Notes: 1. I.S. detectors are polarity sensitive.Notes: 2. There is no requirement for series resistance

on remote LED lines.Notes: 3. The remote LED characteristic differs from

XP95, see page 16.

Supply Voltage:14-22 Volts dc.

Quiescent Current:300µA.

Operating Temperature:–20°C to +40°C (T5).–20°C to +60°C (T4).

Remote LED Current:1mA (internally limited).

Guaranteed Temperature Range:(No condensation or icing)–20°C to +60°C.

BASEEFA Certificate No:BAS02ATEX1289.

Classification:E Ex ia IIC T5 (T4 at Ta ≤ 60°C)

Safety Note

In the United Kingdom, ionisation smoke detectors aresubject to the requirements of the Radioactive SubstancesAct 1993 and to the Ionising Radiations Regulations 1999 madeunder the provisions of the Health and Safety at Work Act 1974.

The detectors, independently tested by the NationalRadiological Protection Board (NRPB), conform to all therequirements specified in the ‘Recommendations forionisation smoke detectors in implementation of radiationstandards’ published by the Nuclear Energy Agency of theOrganisation for Economic Co-operation and Development(OECD) 1977.

There is no limit to the number of ionisation smoke detectorswhich may be installed in any fire protection system.

Storage regulations depend on local standards andlegislation, but, in the UK, up to 500 detectors may bestored in any premises, although there are stipulations onstorage facilities if more than 100 ionisation detectors arestored in one building.

At the end of their recommended working life of ten years,ionisation smoke detectors should be returned to Apollofor safe disposal or disposed of in an otherwise locallyapproved and environmentally safe manner. Please see"A guide to the care, maintenance and servicing of Apolloproducts", PP2055.

Guidance on storage and handling can be given by ApolloFire Detectors and full details can be requested from:Radioactive Substances Regulation FunctionEnvironment AgencyRio House, Waterside DriveAztec West, AlmondsburyBristol BS32 4UD.Outside the UK, please contact the relevant national agency.


Specifications are typical and given at 23°C and 50%relative humidity unless otherwise specified.

Technical Data for the I.S. optical detector is identical tothat for the standard version, except for the informationbelow.




Terminal Functions:L1: positive supply.L2: negative supply and remote LED negative.+R: remote LED positive.Notes: 1. I.S. detectors are polarity sensitive.Notes: 2. There is no requirement for series resistance

on remote LED lines.Notes: 3. The remote LED characteristic differs from

XP95, see page 16.Supply Voltage:14-22 Volts dc.

Quiescent Current:340µA.Operating Temperatures:–20°C to +40°C (T5).–20°C to +60°C (T4).

Remote LED Current:1mA (internally limited).

Guaranteed Temperature Range:(No condensation or icing)–20°C to +60°C.

BASEEFA Certificate No:BAS02ATEX1289.


XP95 I.S. Optical Smoke Detector

Intrinsically Safe Optical Smoke DetectorPart no: 55000-640

Optical smoke detectors incorporate a pulsing LED locatedin a labyrinth within the housing of the detector. Thelabyrinth is designed to exclude light from any externalsource. At an angle to the LED is a photo-diode which, inclear air conditions, does not receive light directly from theLED. The detector transmits a clear air signal to the controlpanel. When smoke enters the labyrinth, light is scatteredonto the photo-diode and the signal to the panel increases.The signal is processed by the electronic circuitry andtransmitted to the control equipment in exactly the sameway as in the case of the ionisation smoke detector.

Full details of the principles of operation and the electricaldescription are published in the XP95 Engineering ProductGuide. XP95 I.S. detectors have the same operatingcharacteristics as the standard versions.

Technical Data – XP95 Intrinsically Safe Optical


Technical Data – XP95 Intrinsically Safe HeatSpecifications are typical and given at 23°C and 50%relative humidity unless otherwise specified.

Technical data for the I.S. heat detector is identical tothat for the standard version, except for the informationbelow.




Terminal Functions:L1: positive supplyL2: negative supply and remote LED negative+R: remote LED positiveNotes: 1. I.S. detectors are polarity sensitive.Notes: 2. There is no requirement for series resistance

on remote LED linesNotes: 3. The remote LED characteristic differs from

XP95, see page 16.

Supply Voltage:14-22 Volts dc

Quiescent Current:300µA.

Operating Temperatures (ambient):–20°C to +40°C (T5).–20°C to +60°C (T4).

Remote LED Current:1mA (internally limited)

Guaranteed Temperature Range:(No condensation or icing)–20°C to +60°C

BASEEFA Certificate No:BAS02ATEX1289


XP95 I.S. Heat Detector

Intrinsically Safe Heat Detector Part no: 55000-440

The XP95 I.S heat detector is distinguishable from XP95 I.Ssmoke detectors by its low air-flow resistance case whichallows good contact between the sensing thermistor and thesurrounding air.

The device monitors temperature by using a single thermistornetwork which provides a voltage output proportional to theexternal air temperature. The voltage signal is processed andtransmitted to the control equipment in the same way as inthe case of the ionisation smoke detector.

Full details of the principles of operation and the electricaldescription are published in the XP95 Engineering ProductGuide. XP95 I.S. detectors have the same operatingcharacteristics as the standard versions.

XP95 I.S. Base

The base for the intrinsically safe range is not identicalwith that for the standard range. This ensures that standarddetectors cannot inadvertently be fitted to an intrinsicallysafe system. For full details of the XP95 addressmechanism refer to the XP95 Engineering Product GuidePP1039.

Fig. 1 Terminal Connections Part no: 45681-215

+R

L1+ L2–

XP95 I.S. Manual Call Points

Intrinsically Safe Manual Call Points

When activated, the intrinsically safe call point not onlyinterrupts the polling cycle to indicate to the control panelthat it has been operated, but also reports its address. Thusan alarm and its location can be reported in less than 0.2seconds.

Full details of the principles of operation and the electricaldescription are published in the XP95 Engineering ProductGuide. XP95 I.S. manual call points have the same operatingcharacteristics as the standard versions. They are availablein two types of housing and in a number of versions.

The standard call point is based on the KAC waterproof modeland is a red, break-glass call point, part no: 55000-940. Thismodel is also available in other colours and a protectivelift-up flap is available. Table 4 gives full details of KAC-based versions and part numbers.

Part No. Colour Type IP Rating

55000-940 Red Without flap 65

55000-942 Yellow Without flap 65

55000-943 Yellow With flap 65

55000-944 Blue/white Without flap 65

55000-945 Blue/white With flap 65

Table 4 KAC-based manual call points

Part No. Colour Type IP Rating

55000-960 Red Break-glass 6655000-962 Yellow Break-glass 6655000-964 Blue Break-glass 6655000-966 Black/yellow Break-glass 66

stripes55000-961 Red Break-glass 66

with flap55000-963 Yellow Break-glass 66

with flap55000-965 Blue Break-glass 66

with flap55000-967 Black/yellow Break-glass 66

stripes with flap55000-970 Red Push-button 6655000-971 Yellow Push-button 6655000-972 Blue Push-button 6655000-973 Black/yellow Push-button 66

stripes

Table 5 MEDC-based manual call points

Part no: 55000-970

Part no: 55000-960

Part no: 55000-940

Technical Data – XP95 Intrinsically SafeManual Call PointsSpecifications are typical and given at 23°C and 50%relative humidity unless otherwise specified.

Technical data for the I.S. manual call point is identicalto that for the standard version, except for theinformation below.Device Part No:See Tables 4 and 5.Supply Wiring:Two wire supply, polarity sensitive.Terminal Functions:L1: positive supplyL2: negative supplyNote: I.S. devices are polarity sensitiveSupply Voltage:14-22 Volts dcQuiescent Current:230µA.Operating Temperature:–20°C to +40°C (T5).–20°C to +60°C (T4).IP Rating:See Tables 4 and 5.BASEEFA Certificate No:BAS02ATEX1290Classification:E Ex ia IIc T5 (T4 at Ta ≤ 60°C)

Dimensions:Part No 55000-940 (KAC-based MCP): 124mm x124mm x 60mm. Weight: approx. 400gPart No 5500-961 (MEDC-based MCP): 126mm x120mm x 67mm (126mm x 120mm x 114mm - pushbutton call point). Weight: approx. 1.20kg

without a stainless-steel protective flap. Table 5 gives partnumbers and full details of MEDC-based call points.

MEDC-based break-glass units have two M20 cable entries onthe bottom face of the back-box. Push button units have oneM20 cable entry on the bottom face and one on the top face.Other cable entry configurations can be provided to special order.

For heavy-duty applications a robust manual call pointbased on a model by MEDC is available. This model ismade of glass-reinforced polyester and may be ordered as abreak-glass or push-button call point and in a variety ofcolours. Break-glass models may be supplied with or

Translator Operation

XP95 Protocol Translator Part no: 55000-855 (single channel)XP95 Protocol Translator Part no: 55000-856 (dual channel)

certification is necessary. The translator falls within thegeneric description “Safe Area Apparatus” on the certifiedsystem diagram.

The translator is housed in a moulded plastic enclosurewhich can be either clipped onto a standard 35mm DIN rail(DIN 46277) or panel mounted by using pull-out latches inthe base. The translator is available in single-channel ordual-channel versions. Each channel should only beconnected to a single intrinsically safe circuit through anappropriate safety barrier. Each channel is thus capable ofsupplying up to twenty XP95 I.S. devices.

A block schematic of the dual-channel translator, showingterminal designations, is given in Fig 2. In the single-channelunit the Channel 2 circuit is not fitted and terminal 12 is not used.

The input to the unit consists of the normal XP95 signal, that isa d.c. voltage on which is superimposed the protocol pulses.

The translator first regulates the d.c. level to 18V. Theincoming protocol pulses are then sensed and re-generatedand shaped with a fixed amplitude of 6V, and superimposedon the 18V d.c. output level.

The 10mA current pulses drawn by the I.S. devices aredetected by the current pulse sensor whose output is used toswitch the 10mA current sink across the input terminalssynchronously with the device current pulse. The currentboosting mechanism is inhibited during the protocol pulsesso that when low resistance loads are connected to thetranslator output the protocol current is not boosted.

A separate current limiting circuit is incorporated in eachchannel which limits the maximum (peak) output current to35mA. This level of current will ensure that safety barrierfuses are not blown in the event of a short-circuit on thebarrier output.

XP95 Protocol Translator

In order to enable the use of standard control and indicatingequipment in intrinsically safe systems, Apollo hasdeveloped a device to “translate” voltage levels from anyloop driver operating within the XP95 limits to levelscompatible with the I.S. requirements. The translator also“boosts” the current pulses returned by the I.S. detectorsfrom 10mA to 20mA, thereby ensuring compatibility withstandard loop driver thresholds.

The translator is a loop-powered device which draws a lowquiescent current and is therefore transparent to both theloop driver and the I.S. detectors. Since the translator is usedwithin the safe area, i.e., before the safety barrier, no


XP95 INTRINSICALLY SAFECOMMUNICATIONS PROTOCOL

The standard XP95 communications protocol is designed tobe very robust and to give the maximum flexibility todesigners of loop driver circuits. The current and voltagelevels used are chosen to be well above noise levels and tooperate in adverse conditions with the minimum of errors.The maximum voltage and current levels used are, however,outside the limits of intrinsically safe systems and it has beennecessary to apply lower limiting values for both currentand voltage in the I.S. range.

The voltage limitation arises because of the need for safetybarriers. The barriers used with Apollo I.S. detectors arerated at 28 volts, the highest rating that is commerciallyavailable. These are used to limit the voltage inside thehazardous area to a (practical) maximum of about 26V DC.Although this is within the standard XP95 protocol specification,it is lower than that provided by most loop drivers.

The safety barrier is also responsible for the currentlimitation because the 28V barriers have a series resistanceof at least 300 ohms. This resistance results in unacceptablevoltage drops if the normal 20mA current pulses are used. Ithas therefore been necessary to reduce the amplitude of thecurrent pulses to 10mA.

The differences between the standard protocol and theintrinsically safe are summarised in Table 6.

Parameter XP95 Standard XP95 I.S.

DC input voltage 17 – 28V 14 – 22V

Pulse voltage 5 - 9V 5 - 9Vpeak to peak

DC + pulse voltage 37V max 26.5V max

Current pulseamplitude 18 – 22mA 9 – 11mA

Input voltage polarity L1 positivepolarity insensitive L2 negative

Table 6 Protocol Variance Data

Technical Data – XP95 Protocol TranslatorSpecifications are typical and given at 23°C and 50%relative humidity unless otherwise specified.

Device Part No:55000-855 (single channel).55000-856 (dual channel).


Supply Voltage:19 to 28 Volts.

Modulation Voltage at Translator:5 to 9 Volts peak to peak.

Input Current (no load condition):2mA max (dual channel).1mA max (single channel).

Output Voltage: (to barrier)16.5 to 19 Volts.

Output Modulation Voltage: (to barrier)5 to 6.5 Volts.

Output Current: (to barrier)0.2 to 30mA

Input Pulse Current: (from barrier)8 to 12mA.

Output Pulse Current: (drawn from loop)17 to 23mA.

Operating Temperature:–20°C to +60°C.

Humidity: (no condensation)10 to 95% relative humidity.

Dimensions:92.5 x 110 x 20mm.

Weights:Approx. 100g.

Materials: (housing)Makrolon 6485 V-0 rated to UL94.

123

456

L1 +

L2

LoopInput

10mACurrent

Sink

CurrentPulseSensor

CurrentLimiter

VoltagePulseSensor

VoltagePulse

Shaper

D.C.Voltage

Regulator

LineDriver

Channel 1Output

–ve

–ve

LineDriver

D.C.Voltage

Regulator

CurrentLimiter

CurrentPulseSensor

10mACurrent

Sink

VoltagePulseSensor

VoltagePulse

Shaper

• • •

•

•

•

•••

•

••

•

•

• •

•Channel 1

Channel 2

+ ve10

7

9

Channel 2Output

+ve

12

Fig. 2 Schematic Diagram – XP95 Protocol Translator


When the dual-channel unit is used it must be rememberedthat the loop input, and the negative side of the output, iscommon to the two channels. It is not possible, therefore, toconnect the two channels to different loops. Although the twochannels have a common input, their outputs are individually

current-limited to 35mA (nominal). Hence, a short-circuit onone channel will cause the loop current to increase by 35mAand as long as the panel is able to support this load thesecond channel will continue to operate normally.

Specifications are typical and given at 23°C and 50% relative humidity unless otherwise specified.

SYSTEM DESIGN

The design of an intrinsically safe fire detection systemshould only be undertaken by engineers familiar with codesof practice for detection systems and hazardous areaelectrical systems. In the UK the relevant standards areBS5839: Part 1 and BS EN 60079-14:2003 respectively.

The fire detection performance of the XP95 I.S. range is thesame as that of its standard counterparts. Performanceinformation given in the XP95 Engineering Product Guide istherefore applicable to the I.S. range.

The BASEEFA certification of the I.S. devices covers theircharacteristics as components of an intrinsically safe systemand indicates that they can be used with a margin of safetyin such systems. The precise way in which the system canbe connected and configured is covered by an additional,“system” certification. The System Diagram, Z20982, seepage 19, details cable parameters and permissibleconfigurations of detectors, manual call points and safetybarriers which are certified by BASEEFA. Any user wishingto install a system outside the parameters given on thissystem diagram cannot make use of the Apollo certificationand should seek independent certification from a competentcertification body.

The BASEEFA system certificate number is Ex94C2444.

Any system installed within the parameters specified in Z20982should be marked in accordance with BS EN 60079-25:2004.The marking should include at least “Apollo XP95 I.S. FireDetection System, BASEEFA No Ex94C2444 SYST”.

In safe area (standard) applications it will be normal practiceto connect the wiring as a loop, with both ends terminatedat the control panel. In the event of an open-circuit fault it isthen possible to drive both ends simultaneously. In ahazardous area it is not possible to use a loop configurationbecause the potential to feed power from each end of the loopwould double the available energy in the hazardous areaand contravene the energy limitations of the I.S. certification.All XP95 I.S. circuits must therefore be connected as spursfrom the safe area loop or as radial connections from thecontrol panel.

It is recommended, for the highest system integrity, that each I.S.circuit be restricted to a single zone and that the connectionfrom the safe area loop to the I.S. spur be protected on eachside by XP95 isolators. The DIN-rail dual isolator (55000-802)is particularly suited to this application. This configuration,shown in Fig 3, will conform fully with the requirements ofBS5839:Part 1 and with the European GuidelinesDD CEN/TS 54-14:2004 since a single wiring fault willresult in the loss of only one zone of detection.

In certain circumstances it may be possible for the simplerconfiguration, shown in Fig 4, to be used. This arrangementmay include single or dual-channel translators, housed,together with the critical wiring, in a robust mechanicalenclosure. For further advice, please contact the TechnicalSales department at Apollo.

Fig. 3 Schematic Wiring Diagram of XP95 I.S. Circuit toBS5839

Fig. 4 Schematic Wiring Diagram of XP95 I.S. Circuit usingDual-channel Protocol Translator

Fig. 5 Detail of Schematic Wiring Diagram of I.S. Zone

2 core

I.S. zone n

XP95Isolator

XP95 ProtocolTranslator

XP95 I.S.Detector

SafetyBarrier

I.S. zone n + 1 I.S. zone n + 2

Sealed enclosure to IP54 or higher

XP95 Loopin Safe Area

2 core

I.S. zones: n n + 1 n + 2 n + 3XP95

IsolatorXP95 Protocol

Translator

SafetyBarrier

XP95 Dual-channelProtocol Translator

XP95 I.S.Detector

High-integrityWiring

XP95 Loop inSafe Area


Fig. 5 Detail of Schematic Wiring Diagram of I.S. Zone

+R

L1+ L2–

+R

L1+ L2–

∩∪

OptionalRemoteLED

XP95 Loop+ –

– +

P & F KFDO barrier(view from top)

– +

Protocol translator(view from top)

Any loading resistorshould be connectedbetween L1 and L2of the first base

1234 5 6

78910 11 12

Galvanically isolated barriers (also known as transformerisolated barriers) differ from conventional shunt zenerbarriers in that they provide electrical isolation between theinput (safe area) and the output (hazardous area). This isachieved by the use of a D.C./D.C. converter on the inputside which is connected to the hazardous area through avoltage-and power-limiting resistor/zener combinationsimilar to a conventional barrier.

The galvanic isolation technique means that the circuit doesnot need a high integrity (safety) earth and that the intrinsicallysafe circuit is fully floating. Earth leakage problems for controland indicating equipment are therefore eliminated if thistype of interface is used.

Note: Although the circuit does not require a high-integrityearth, it is permissible to earth either side of the hazardousarea circuit if required by other system considerations.

Although galvanically isolated barriers are widely used withconventional fire detectors the pulse response of standardproducts has been too slow to allow their use in analogueaddressable systems. Apollo has worked closely withPepperl + Fuchs in the development of a special galvanicallyisolated barrier which freely transmits the XP95 protocolpulses without introducing severe voltage drops.

This interface is available as single or dual channel versionsand is recommended for any application in which directearth connections are not acceptable. The Pepperl + Fuchstype numbers are KFDO-CS-Ex1.54 and KFDO-CS-Ex2.54for the single and dual channel devices respectively. Bothversions are BASEEFA certified under certificate numberBAS00ATEX7087. (The KFDO- types have replaced theearlier KHDO- types.)

The galvanically isolated barrier is a two-wire device whichdoes not need an external power supply. Current drawnfrom the XP95 loop by the barrier itself is less than 2mAwhen loaded as specified by the manufacturer. The housingis a rail-mounted type identical to that used for the protocoltranslator.

TYPES OF SAFETY BARRIERThe certified system configurations allow for three types ofsafety barrier, each of which has its own advantages anddisadvantages. A brief outline of their characteristics isgiven below.


This is the most basic type of barrier and therefore the lowestin cost. Being passive devices, they also impose the minimumof restrictions on the operation of the fire detectors. Thus,single channel barriers are available either as positive ornegative polarity where the polarity refers to the polarity of theapplied voltage relative to earth. The significance of this is thatone side of the barrier must be connected to a high-integrity(safety) earth. Although this earth connection has no effect onthe operation of the XP95 I.S. devices and is not needed fortheir correct operation, it may not be acceptable to theoperation of the control and indicating equipment. This isparticularly true if the control equipment incorporates earth-leakage monitoring and even without this feature the earthingof the loop may cause unwanted cross-talk between loops.

If the earth connection is not acceptable then the A.C. orisolating barriers should be used.

Single Channel 28V/300 Ω Barrier

Star-connected A.C. Barrier

A.C. barriers are also passive devices and must still beconnected to a high-integrity safety earth. However, they aredesigned to allow either positive or negative voltages withrespect to earth and under normal conditions provide aconnection to earth via a reverse-biased diode, rather thandirectly.

The disadvantage of this type of barrier is that the end-to-endresistance is nominally 1200 ohms compared with the 300ohms of the single channel type. This high resistance resultsin an extra voltage drop in the circuit.

This type of barrier is not recommended for general use.

Galvanically Isolated Barrier

APPROVED SAFETY BARRIERSThe system certification includes a generic specification forbarriers, two additional, individually approved barriers andtwo transformer isolated current repeaters (ie, barriers).

The generic specification is:

any shunt zener diode safety barrier certified by BASEEFA orany EEC approved certification body to

E Ex ia IIC

having the following or lower output parameters:

Uz = 28V

I max:out = 93.3mA

W max:out = 0.67W

In any safety barrier used the output current must be limitedby a resistor ‘R’ such that

I max:out = Uz

R

A number of single-channel barriers meet this specificationand examples are given below:

Supplier Type Polarity Mounting

Pepperl & Fuchs Ltd Z728 +ve DIN-rail77 Ripponden Road Z828 -ve DIN-railOldham Z428/Ex +ve DIN-rail/surfaceLancs OL1 4EL Z528/Ex -ve DIN-rail/surface0161 633 6431

Measurement Technology Ltd MTL728+ +ve BusbarPower Court MTL7028+ +ve DIN-railLuton MTL7128+ +ve DIN-railBedfordshire LU1 3JJ01582450 042

Weidmüller (Klippon S951 +ve (Cat No 980805) DIN-rail/surfaceMicrosystems) Ltd +ve (Cat No 980806)1 Abbeywood Road E951APOS +ve DIN-rail/surfaceKings Hill E951ANEG -ve DIN-rail/surfaceWest MallingKent ME19 6EX01732 844 444

Table 7 28V/300V single channel safety barriers

The two individually approved barriers are:

1. Pepperl & Fuchs Z978Star connected shunt zener diode safety barrier,28V/600V, dual channel. BASEEFA certificate no.Ex 93C2412, BAS01ATEX7005.

2. Measurement Technology Ltd. MTL 778Star connected shunt zener diode safety barrier,28V/600V. BASEEFA certificate no. Ex 832452,BAS01ATEX7202.

The transformer isolated current repeaters (barriers) aredescribed on page 13.


SAFETY EARTH

Single channel and star connected A.C. safety barriers mustbe connected to a high integrity earth by at least one andpreferably two copper cables, each of cross sectional area of4mm2 or greater. The connection must be such that theimpedance from the connection point to the main powersystem earth is less than one ohm.

Intrinsically safe circuits in the hazardous area should beinsulated from earth and must be capable of withstanding a500V RMS A.C. test voltage for at least one minute. Whenusing armoured or copper sheathed cables, the armour orsheath is normally isolated from the safe area busbar.

GroupCapacitance Inductance L/R Ratio

µF mH µH/ohm

IIC 0.083 4.2 55

IIB 0.65 12.6 165

IIA 2.15 33.6 440

Table 8 Limits for Energy Stored in Cables.

SizeCapacitance Sheath

Cable Type Conductor resistance Inductance µF/km ResistanceCore mm2 ohm/km/core mH/km core core ohm/kmto core to sheath

MICC Pyrotenax light duty 2 1.5 12.1 0.534 0.19 0.21 2.77

MICC Pyrotenax heavy duty 2 1.5 12.1 0.643 0.13 0.17 1.58

Pirelli FP200 all 1.5 12.1 0.08 0.15

PVC sheathed and insulated to BS 6004 all 1.5 12.1 0.77 0.09

Table 9 Examples of electrical characteristics of cables commonly used in fire protection systems.

WIRING AND CABLE TYPES

It is not permitted to connect more than one circuit in thehazardous area to any one safety barrier and that circuitmay not be connected to any other electrical circuit.Both separate and twin cables may be used. A paircontained in a type ‘A’ or ‘B’ multicore cable (as defined inclause 12.2.2 of BS EN 60079-14:2004) may also be used,provided that the peak voltage of any circuit containedwithin the multicore does not exceed 60V.

The capacitance and either the inductance or theinductance to resistance (L/R) ratio of the hazardous areacables must not exceed the parameters specified in Table 8.The reason for this is that energy can be stored in a cableand it is necessary to use cable in which energy stored isinsufficient to ignite an explosive atmosphere.

To calculate the total capacitance or inductance for thelength of cables in the hazardous area, refer to Table 9,which gives typical per kilometer capacitance andinductance for commonly used cables. (Note: All XP95 I.S.devices have zero equivalent capacitance and inductance.)


INSTALLATION

It is important that the XP95 I.S. detectors are installed in sucha way that all terminals and connections are protected to atleast IP20 when the detector is in the base. Special care mustbe taken with the rear of the mounting base where live metalparts (rivets) may be accessible. Flush mounting of the base ona flat surface will provide the required degree of protection.

If the base is mounted on a conduit box (e.g. BESA box orsimilar) whose diameter is less than 85mm then the baseshould be fitted with a Series 60/XP95 Backplate (Apollopart number 45681-233). Use of the backplate will preventaccess to the metal parts and will also protect the rear of thebase from water ingress. The conduit box available fromApollo, part no. 45681-204, is also acceptable for mountingI.S. bases. Apollo also supply a range of deckhead mountingboxes. For more information, please refer to PP1089, basesand accessories brochure.

Fig. 6 shows permissible methods of installing intrinsicallysafe detector bases.

Note that the earth terminal in the base is provided forconvenience where continuity of a cable sheath or similar isrequired. It is not necessary for the correct operation of thedetector nor is it provided as a termination point for a safetyearth.

Base with backplate and BESA Box

Base fitted flush to soffit

Base fitted to conduit box

Fig. 6 Permissible methods of mounting I.S. bases

StandardBESA Box

I.S. BasePart no.45681-215

BackplatePart no. 45681-233

I.S. BasePart no. 45681-215

Conduit BoxPart no.45681-204

I.S. BasePart no.45681-215

Max. number of Max (total) deviceLEDs illuminated load (mA)

0 8.01 7.02 6.03 5.04 4.05 3.0

Table 10 Maximum Loading (28V/300V single channel barrier).

MAXIMUM LOADING OF I.S. CIRCUIT

Because of the finite resistance of the safety barrier, therewill be a limit to the current drain which can be toleratedbefore the voltages on the circuit fall outside the specifiedlimits for XP95 I.S. devices. Two components of the currentdrain must be considered, namely the standing current ofthe devices by themselves and the maximum drain causedby alarm LEDs being illuminated. The standing current ofthe devices can be calculated by taking the sum of theindividual device currents on the circuit, as given in thesection “Technical data” for each product.

The maximum number of LEDs that can be illuminatedsimultaneously should ideally be limited by the panel software.Because the LED load is often the limiting factor in determiningthe voltage drop, the later versions of the XP95 I.S detectorsare fitted with high efficiency LEDs. This has allowed areduction from 2mA to 1mA in the LED current. It is importantwhen fitting remote LEDs that high efficiency types are used.

Table 10 shows the maximum device standing current whichcan be supported for varying numbers of LEDs illuminated.


REMOTE LED CONNECTION

A drive point is provided on each of the XP95 I.S. detectorsfor a remote LED indicator. For connection details see Fig. 5.The indicator must be a standard high-efficiency red LEDand does not require a series limiting resistor since current islimited within the detector to approximately 1mA. Theremote LED cannot, as in the standard XP95 range, becontrolled independently from the integral LED since it iseffectively connected in series with the integral LED. Thebenefit of this configuration is that illumination of the remoteLED does not increase the current drawn from the loop.

The system certification allows for the use of any LEDindicator having a surface area between 20mm2 and 10cm2

which covers all commonly used case styles from T1 (3mm)upwards but would exclude some miniature and surfacemounted types. Additional requirements of the certification arethat the LED and its terminations must be afforded a degree ofprotection of at least IP20 and must be segregated from othercircuits and conductors as defined in BS EN 60079-14:2003.

The Apollo MiniDisc Remote Indicator (53832-070) is suitable.


MiniDisc Remote Indicator

MiniDisc Remote Indicator Part no: 53832-070

The miniDisc remote indicator is only 20mm high and80mm in diameter. It comproses two parts–the base whichis installed onto a wall or soffit and the lid which is fitted tothe base with a bayonet lock.

An anti-tamper screw in the lid locks the unit together. A1.5mm hexagonal driver, part number 29600-095, isavailable from Apollo.

Tow pairs of keyholes are provided–one for 50mm and theother for 60mm fixing centres.

The MiniDisc Remote Indicator is polarity sensitive.Connect positive line to Terminal A or B and negative line toTerminal C. See Table 11.

C (–)

B A (+)

LED

Detector Range Connections

Series 60, Series 65, Série 50 A & CAlarmSense B & COrbis A & CSeries 60 Intrinsically Safe A & C

XPlorer A & CXP95 A & CDiscovery A & CXP95 Intrinsically Safe B & C

Voltage, A & C 5–36VMax curent, B & C 25mA, up to 40°COperating temperature –10° to +60°C

Table 11 MiniDisc Remote Indicator electrical connections.


SERVICING

Servicing of I.S. fire detectors may be carried out only by aBASEEFA authorised body. In practical terms this means thatApollo XP95 I.S. fire detectors may be serviced only byApollo at its factory. Servicing of the fire protection systemshould be carried out as recommended by the code ofpractice BS 5839: Part 1 or other local regulations in force.For more information on servicing Apollo detectors, pleaserefer to the care, service and maintenance guide, PP2055.

APPROVALS

XP95 I.S. detectors have been approved by LPCB to EN54and the XP95 I.S. manual call point, part no 55000-940, isLPCB approved to BS5839 : Part 2. These products havealso been approved for marine use by the following bodies:American Bureau of ShippingBureau VeritasDet Norske VeritasGermanisher LloydLloyds Register of Shipping

Maritime and Coastguard Agency

Details of approvals held are available on request.

The product Certification Technical Files for the XP95 ISrange are held by BASEEFA in accordance with therequirements of the ATEX Directive 94/9/EC. All detectorsand manual call points are marked.

XP95 I.S. SYSTEM DRAWING

Note: P + F Z378/Ex has been superseded by P + F Z978


PP1095/2005/Issue 4

Further information on Apollo detector ranges is available. Please quote the relevant PP number when ordering.

PRODUCT PUBLICATION PUBLICATION TYPENUMBER

XP95 Range PP1039 Engineering Product GuidePP1040 General Sales Brochure

XP95 I.S. PP1094 Sales LeafletSeries 60 I.S. PP2028 PIN SheetMiniDisc Remote Indicator PP2074 PIN SheetBases and Accessories PP1089 BrochureAll PP2055 A Guide to the care, service

and maintenance of ApolloProducts.

Deckhead Mounting Box PP2040 PIN Sheet

36 Brookside Road, Havant, Hampshire PO9 1JR, UK. Tel: +44 (0)23 9249 2412. Fax: +44 (0)23 9249 2754. Email: [email protected] Website: www.apollo-fire.co.uk

Apollo GmbH, Am Anger 31, 33332 Gütersloh, Germany. Tel: +49 5241 33060. Fax: +49 5241 330629

Assessed to ISO 9001: 2000Certificate number 010

© Apollo Fire Detectors Ltd 1999 - 2005

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